Table 1.
Methodological quality criteria evaluated of randomly selected randomized controlled trials (RCTs) published during the 30-year study period*
| 1975 (n = 10) | 1980 (n = 10) | 1985 (n = 10) | 1990 (n = 10) | 1995 (n = 10) | 2000 (n = 10) | 2005 (n = 10) | |
|---|---|---|---|---|---|---|---|
| Jadad criteria (modified) | |||||||
| Description of randomization | 5 | 5 | 6 | 3 | 4 | 2 | 3 |
| Double blinding | 5 | 2 | 3 | 4 | 3 | 3 | 3 |
| Description of blinding† | 2 | 2 | 2 | 3 | 3 | 3 | 2 |
| Description of withdrawals and drop-outs | 7 | 4 | 5 | 3 | 8 | 8 | 7 |
| Additional criteria | |||||||
| Eligibility | 10 | 10 | 10 | 10 | 10 | 10 | 10 |
| Interventions | 10 | 10 | 10 | 10 | 10 | 10 | 10 |
| Outcomes | 10 | 10 | 10 | 10 | 10 | 10 | 10 |
| Allocation concealment | 4 | 1 | 3 | 2 | 5 | 2 | 2 |
| Baseline data | 7 | 9 | 8 | 10 | 10 | 10 | 10 |
| Adverse events | 9 | 8 | 7 | 8 | 7 | 10 | 7 |
| Power of the study | 0 | 0 | 0 | 1 | 3 | 4 | 4 |
| Statistical significance | 5 | 6 | 9 | 7 | 10 | 10 | 8 |
| Conflicts of interest and funding of the research | 9 | 5 | 4 | 6 | 5 | 8 | 9 |
*
Numbers in the columns denote the result of the methodological quality of the evaluated RCTs based on the grading system we used and explained in Methods.
†
The numbers regarding quality of blinding should be interpreted in relation to the numbers of trials which were double blind [e.g. in 1975 2/5 (40%) of maximum points for double blinding were given, vs. 2/2 in 1980 (100%)].